Prior to the present invention, silicon-silicon carbide composites made to a specific shape were made in accordance with the procedure shown in Laskow et al, U.S. Pat. No. 4,141,948, assigned to the same assignee as the present invention, where molten silicon was allowed to infiltrate into a mold containing a carbon fiber preform. The carbon fiber preform of Laskow et al was generally made by use of an organic binder which could be baked out of the preform prior to molten silicon infiltration or which could be allowed to react during the silicon carbide formation, resulting in the production of organic gases which had to be removed from the furnace during the composite formation. Another procedure is shown by Weaver, U.S. Pat. No. 3,725,015 which involves the production of cold forming a carbon fiber preform using an organic binder prior to the reaction of the preform with a metal to produce a metal carbide. Those skilled in the art know that the presence of organic binders often result in air pollution and contaminate the atmosphere or the equipment used in making the shaped metal carbide part.
The present invention is based on the discovery that shaped silicon-silicon carbide refractories do not have to be made by the use of a carbon fiber preform or by the employment of an organic binder prior to molten silicon infiltration by using a putty-like mixture of powdered silicon, particulated carbon, water and optionally silicon carbide powder. The putty can be applied onto the surface of a silicon carbide refractory supporting base structure, or a material having an expansion coefficient similar to silicon carbide, such as about 5.5.times.10.sup.-6 per degree C., contoured to provide the final shape desired in the refractory part. After it has dried, the putty remains self-supporting. The total composite of the silicon carbide part and applied putty can then be placed in a furnace and heated to molten silicon infiltration temperatures to produce a shaped silicon-silicon carbide refractory.